Node.js MySQL Select From 语句
从表格中选择数据
要从MySQL中的表中选择数据，请使用 "SELECT" 语句。
实例
从 "customers" 表中选择所有记录，并显示结果对象:
var mysql = require('mysql');
var con = mysql.createConnection({
host: "localhost",
user: "yourusername",
password: "yourpassword",
database: "mydb"
});
con.connect(function(err) {
if (err) throw err;
con.query("SELECT * FROM customers", function (err, result, fields) {
if (err) throw err;
console.log(result);
});
});
运行实例 »
SELECT * 将返回所有列
将上述代码保存在名为 "demo_db_select.js" 的文件中，然后运行该文件:
运行 "demo_db_select.js"
C:\Users\Your Name>node demo_db_select.js
返回结果:
[
{ id: 1, name: 'John', address: 'Highway 71'},
{ id:
2, name: 'Peter', address: 'Lowstreet 4'},
{ id: 3, name: 'Amy',
address: 'Apple st 652'},
{ id: 4, name: 'Hannah', address:
'Mountain 21'},
{ id: 5, name: 'Michael', address: 'Valley 345'},
{ id: 6, name: 'Sandy', address: 'Ocean blvd 2'},
{ id: 7,
name: 'Betty', address: 'Green Grass 1'},
{ id: 8, name: 'Richard',
address: 'Sky st 331'},
{ id: 9, name: 'Susan', address: 'One way
98'},
{ id: 10, name: 'Vicky', address: 'Yellow Garden 2'},
{ id: 11, name: 'Ben', address: 'Park Lane 38'},
{ id: 12, name: 'William',
address: 'Central st 954'},
{ id: 13, name: 'Chuck', address:
'Main Road 989'},
{ id: 14, name: 'Viola', address: 'Sideway
1633'}
]
选择列
要仅选择表中的某些列，请使用 "SELECT" 语句，后跟列名。
实例
从 "customers" 表中选择名称和地址，并显示:
var mysql = require('mysql');
var con = mysql.createConnection({
host: "localhost",
user: "yourusername",
password: "yourpassword",
database: "mydb"
});
con.connect(function(err) {
if (err) throw err;
con.query("SELECT name, address FROM customers", function (err, result, fields) {
if (err) throw err;
console.log(result);
});
});
运行实例 »
将上述代码保存在名为 "demo_db_select2.js" 的文件中，然后运行该文件:
运行 "demo_db_select2.js"
C:\Users\Your Name>node demo_db_select2.js
返回结果:
[
{ name: 'John', address: 'Highway 71'},
{ name: 'Peter', address: 'Lowstreet 4'},
{ name: 'Amy',
address: 'Apple st 652'},
{ name: 'Hannah', address:
'Mountain 21'},
{ name: 'Michael', address: 'Valley 345'},
{ name: 'Sandy', address: 'Ocean blvd 2'},
{
name: 'Betty', address: 'Green Grass 1'},
{ name: 'Richard',
address: 'Sky st 331'},
{ name: 'Susan', address: 'One way
98'},
{ name: 'Vicky', address: 'Yellow Garden 2'},
{ name: 'Ben', address: 'Park Lane 38'},
{ name: 'William',
address: 'Central st 954'},
{ name: 'Chuck', address:
'Main Road 989'},
{ name: 'Viola', address: 'Sideway
1633'}
]
Result 记录集对象
从上面示例的结果中可以看到，result 对象是一个数组，包含作为记录集对象的每一行。
要返回第三条记录的地址，只需选择第三个数组对象的 address 属性:
实例
返回第 3 条记录的地址:
console.log(result[2].address);
返回结果:
Apple st 652
Fields 字段对象
回调函数的第三个参数是一个数组，其中包含有关结果中每个字段的信息。
实例
从 "customers" 表中选择所有记录，并显示 fields 对象:
var mysql = require('mysql');
var con = mysql.createConnection({
host: "localhost",
user: "yourusername",
password: "yourpassword",
database: "mydb"
});
con.connect(function(err) {
if (err) throw err;
con.query("SELECT name, address FROM customers", function (err,
result, fields) {
if (err) throw err;
console.log(fields);
});
});
运行实例 »
将上述代码保存在名为 "demo_db_select_fields.js" 的文件中，然后运行该文件:
运行 "demo_db_select_fields.js"
C:\Users\Your Name>node demo_db_select_fields.js
返回结果:
[
{
catalog: 'def',
db:
'mydb',
table: 'customers',
orgTable: 'customers',
name: 'name',
orgName: 'address',
charsetNr: 33,
length: 765,
type: 253,
flags: 0,
decimals: 0,
default: undefined,
zeroFill: false,
protocol41: true
},
{
catalog: 'def',
db: 'mydb',
table: 'customers',
orgTable: 'customers',
name: 'address',
orgName: 'address',
charsetNr: 33,
length: 765,
type:
253,
flags: 0,
decimals: 0,
default: undefined,
zeroFill: false,
protocol41: true
}
]
从上面示例的结果可以看出，fields 对象是一个数组，包含每个字段作为对象的信息。
要返回第 2 个字段的名称，只需参考第 2 个数组项的 name 属性:
实例
返回第 2 个字段的名称:
console.log(fields[1].name);
返回结果:
address
